Infections of the lower respiratory tract are common. These include acute infections, such as pneumonia or bronchitis. These also include chronic infections, such as infections associated with cystic fibrosis or chronic obstructive pulmonary disorder (COPD). These chronic infections affect the lungs and can eventually lead to death.
Administration of antibiotics is known to reduce the rate of lung tissue degradation and thereby enhance the survival rate of those suffering from chronic infections of the lungs and airways. Such antibiotics are typically administered orally or through injection. But these methods involve certain shortcomings. In particular, these methods do not permit specific targeting of the infected areas of the lower respiratory tract. It would be desirable to be able to deliver the antibiotic directly to the infected airways and lungs. In this way, smaller doses could be used, and dosing would occur with less frequency.
Inhalation provides one possible solution to this problem. Yet this poses other problems. For example, if the microparticles are sufficiently small to reach the lung, then the particles are of an ideal size to be eliminated from the lungs via macrophage uptake. Thus, there is a continuing need for solid compositions that can be used to deliver a dose of antibiotic to the lower respiratory tract, including the deep lung, that will substantially resist elimination from the lungs by macrophage uptake.